A wide variety of implantable medical devices (IMDs) are commercially available for clinical implantation, including cardiac pacemakers, cardioverter/defibrillators having pacing capabilities, other electrical stimulators including spinal cord, deep brain, nerve, and muscle stimulators, drug delivery systems, cardiac and other physiologic monitors, cochlear implants, etc. Such IMDs often contain a battery powered component that is implanted subcutaneously at a surgically prepared site, referred to as a “pocket”. Associated devices, such as medical leads and catheters, extend from the subcutaneous site to other subcutaneous sites or deeper into the body to organs or other implantation sites.
The surgical preparation and initial or replacement IMD implantations are conducted in a sterile field, and the IMD components are packaged in sterile containers or sterilized prior to introduction into the sterile field. However, despite these precautions, there always is a risk of introduction of microbes into the pocket. Surgeons therefore typically apply disinfectant or antiseptic agents to the skin at the surgical site prior to surgery, directly to the site before the incision is closed, and prescribe oral antibiotics for the patient to ingest during recovery.
Despite these precautions, infections do occur. In addition, once the pocket becomes infected, the infection can migrate along the lead or catheter to the heart, brain, spinal canal or other location in which the lead or catheter is implanted. Such a migrating infection can become intractable and life-threatening, requiring removal of the IMD in the pocket and associated devices, such as leads and catheters. Removal of a chronically implanted lead or catheter can be difficult and dangerous. Aggressive systemic drug treatment is also provided to treat the infection.
Impregnating, coating or otherwise disposing one or more anti-infective agent in, on or about an IMD has been proposed. Some such IMDs are currently commercially available. However, the use of anti-infective agents with permanently or temporarily implantable IMDs raises concerns such as development of strains of microbes resistant to the anti-infective agents and the development of allergic reactions to the anti-infective agents associated with the IMD. The presence of low levels of anti-infective agents over time raises concerns regarding the development of resistant strains of microbes, and large amounts or the presence of anti-infective agent over time raises concerns regarding development of an allergic reaction.